Web outfeed processing system for high performance printer

ABSTRACT

A cabinet is provided downstream of a high speed laser printer, and provides an environmentally controllable environment for a web that must be “moisturized” before being fed to a downstream device for further processing. A single web loop is gravity biased as well as acted on by a constant force spring to accommodate abrupt speed changes in the web. The depth of the web loop is of sufficient height to accommodate reversals in web direction necessitated by the laser printer.

BACKGROUND OF INVENTION

[0001] Modern high speed laser printers have developed at a pace which has outstripped the performance capabilities of present-day web rewinding systems. One solution has been proposed by the Assignee herein, whereby two or more tension-free web loops are provided downstream of the printer to accommodate the variations in output speed of such laser printers. U.S. Pat. No. 5,992,789 issued Nov. 30, 1999. However, the technology of web handling systems must be further improved to accommodate the latest output web speed and displacement of today's high speed, high performance laser printers. For example, one such high performance laser printer now marketed by OCÉ has a requirement that the web take-up system must accommodate not only abrupt changes in speed, but reversals in direction on the order of several meters.

[0002] While tension-free loops generally afford the most efficient way of accommodating accumulated sections of web, not only during radical speed changes, but also during reversals in direction of the web, the accelerations and decelerations of the web in the latest printers have been found to exceed the capabilities of present-day tension-free loop controllers such as that referred to in, U.S. Pat. No. 5,992,789.

SUMMARY OF THE INVENTION

[0003] In accordance with the present invention, a relatively tall cabinet is provided so as to ensure an environmentally controllable space within which to accommodate a paper web that will be subjected to accelerations and decelerations on the order of magnitude of gravity itself, and to accommodate as well reverse motion of the web back into the printer on the order of several meters. The cabinet is preferably on the order of two meters in height and includes provision for maintaining a relatively high degree of humidity inside the cabinet as to counteract the drying affect on the paper web of the laser printer. The cabinet includes cooling capability as well, but without the usual moisture removal typical of present-day air conditioning systems. In its place, a source of shop air is expanded to create a cooling effect without adversely affecting the relatively humid air that is maintained in the cabinet by use of a conventional humidifier. This combination avoids the need for running the paper web through a solution to increase the humidity of the paper web emanating from the printer as is sometimes done in present-day print shops.

[0004] Instead of one or more tension-free loops the present invention portrays a weighted bar to provide a gravity-biasing force downwardly on the paper web loop. Although this is a known practice in the printing technology generally, the present invention adds a constant force spring-biasing means to the weighted roller. The acceleration and deceleration of the paper web can sometimes exceed the forces and acceleration otherwise expected from gravity itself, hence the need for constant force spring biasing means.

[0005] A control panel is preferably provided on the cabinet and includes status lites which indicate to the operator the status of the printer upstream of the cabinet, and also the status of downstream devices to which the paper web will be delivered, namely cutters, job separators, rewinders, fan folders, booklet makers, and other such paper web handling devices known to this art.

[0006] The control panel also displays certain conditions within the cabinet itself, namely the temperature, the humidity, and the output of a transducer probe or electrical resistance measuring device, provided adjacent the paper web and capable of measuring the humidity of the paper web itself. It should be noted that the temperature controlled atmosphere in the cabinet, required as per the present invention, is necessary to increase the humidity of the paper as a result of the drying effects on the paper web from the laser printer.

[0007] The control panel also preferably includes a laptop computer interface which will permit the operator to read out past histories of the computerized input to the status lites and other internal circuitry associated with control of the system components. The operator control panel serves to provide the user with an understanding of the effectiveness of the unit during the preceding day or other convenient timeframe.

[0008] Another optional feature of the present invention lies in the cabinet affording a convenient location along the path of the web from the printer to the downstream device for taking intermittent or continuous video inspection shots of both sides of the web, either for calibration purposes or for any other reason. Further, edge sensors are employed to provide input to the drive roller which is “steerable” in order to assure that the web tracks properly through the apparatus of the present invention. The display screen provided on the control panel is preferably of the touch-pad variety so as to allow control of the temperature and humidity within the cabinet, and for control of the video inspection cameras.

[0009] The control system for the loop in the cabinet may be similar to that for controlling the loops in the above U.S. Pat. No. 5,992,789. An ultrasonic transducer serves the bottom of the loop and provides an input to the control circuit for changing the speed of and direction or rotation for the drive roller.

BRIEF DESCRIPTION OF THE DRAWING

[0010]FIG. 1 shows in schematic fashion a cabinet containing the components of the present invention, this view being a side elevation, with the path taken by the web shown in solid lines entering the cabinet and leaving the cabinet, and showing in broken lines the path taken by the web in forming the web loop.

DETAILED DESCRIPTION OF THE DRAWINGS

[0011] Turning now to the drawing in greater detail, FIG. 1 shows a high performance laser printer 10 of the type which imparts heat to the paper web, and which requires changes in, not only the speed of the web exiting the printer, but reversals in direction for the web all in accordance with the operation of the high performance laser printer itself.

[0012] The web W enters the cabinet 12 through a slot 12 _(A) at the input side of the cabinet, and passes by a transducer, in the form of a compactive probe, which is adapted to measure the moisture content (or dryness) of the paper web. The output from the transducer is fed to a control circuit 14 which in turn is capable of controlling an air cooling unit 16 of the type operating from a source of air under pressure (such as shop air at 20 pounds plus or minus) that utilizes a valve to expand the air and thereby achieve cooling of the environment within the cabinet 12.

[0013] The cabinet 12 also includes a humidifier 18 for introducing moisture into the atmosphere within the cabinet so as to increase the moisture content of the web and avoid the excessive dryness created in the web by the laser printer 10.

[0014] The web undergoes a loop in the cabinet created by a weighted bar 20 provided in the web loop, and the position of the weighted bar and web loop is sensed by an ultrasonic transducer 22. The output from this ultrasonic transducer is fed to the control circuit 14 for regulating the speed of the motor M, and hence the speed of idler rotation of the drive roller 24. The web loop is defined between the drive roller 24 and an idle roller 26 over which the web is entrained as it passes through the cabinet from right to left and as indicated by the broken line in FIG. 1.

[0015] In the front side of the cabinet 12 a control panel 30 is provided, and that control panel has an interactive screen 30 _(A) as described previously, together with the status lites 30 _(B) also as described above.

[0016] The weighed bar 20 is acted upon by gravity to create a biasing force on the web that allows the web to be accommodated within the cabinet from movement of the bar between the positions shown. To increase the force exerted on the web a constant force spring 32 is provided so as to act on the weighted bar 20 and increase the force downwardly on the web in the event that accelerations of the web due to gravity is not sufficient for accommodating the speed changes required at the laser printer

[0017] In further accordance with the present invention cameras are provided to view one or both sides of the web passing along the path dictated by the cabinet components described previously. Operation of these video cameras can be provided for at the panel 30. The cabinet also preferably include suitable means for neutralizing any static electricity build up on the web. Such a device is conveniently provided at or near the mounting structure for the cameras (not shown).

[0018] In light of the above disclosure it will be understood by those skilled in the art that the invention may be practiced otherwise than as specifically described herein, and it is therefore the intent of the application that the invention be defined by the scope of the appended claims. 

What is claimed is:
 1. A web processing system for use with a high performance printer of the type adapted to output a printed web at a speed which varies widely, and which pulls the web back into the printer periodically for purposes peculiar to the printer, said system comprising: a vertically elongated cabinet defining an internal enclosure, and having on one lateral side thereof a slot for receiving the web from a laser printer, and on an opposite side a slot through which the web pass to a downstream device, at least one elongated web loop within said cabinet defined by a drive roller on one side of the cabinet, and an idler roller generally opposite the drive roller, the web loop being further defined by a downwardly biased weighted bar engaging the lower portion of the loop, and at least one ultrasonic sensing device for sensing the depth of the loop.
 2. The system of claim 1 further including a control circuit for keeping the height of the downwardly biased bar within predetermined limits as a result of changing the speed of the drive roller, and means for controlling the atmospheric conditions within the cabinet so as to maintain a predetermined relative humidity for the paper web inside the cabinet, and for maintaining the temperature of the web within the cabinet within predetermined ranges.
 3. The combination according to claim 1 further including at least one video camera in the cabinet to at least one side of the paper web through said cabinet.
 4. The combination according to claim 1 wherein a control panel is provided on a front face the cabinet between the input and output sides thereof, said control panel including status lites as well as a touch pad LED control panel so that the operator can observe by warning lites indicative of the humidity and temperature of the paper web moving through said cabinet.
 5. The combination according to claim 1 further characterized by edge sensor means within the cabinet to detect movement of the paper web laterally of the above-mentioned drive roller and means for tilting the drive roller relation the direction of web travel so as to steer the web into a position most efficient for the paper web as it travels around a circumferential portion of the drive roller.
 6. The combination according to claim 1 wherein said status lites indicate predetermined conditions of the laser printer upstream of the cabinet, and indicate conditions of downstream devices for further processing the paper web emanating from the cabinet.
 7. The combination according to claim 1 wherein said cabinet includes a computer processing unit for operating a control panel, and an interface plug for allowing a personal computer to be linked to the processing unit within the cabinet.
 8. The combination according to claim 1 wherein said biased bar defining the lower end of said web loop is biased by gravity.
 9. The combination according to claim 1 wherein said biasing force acting on said web loop bar is supplemented by a constant force spring means acting on the weighted bar. 